Dental anchor apparatus and method

ABSTRACT

A dental anchor apparatus having a one or two part endosseous implant securable in a patient&#39;s mouth and a retention member which is releasably engageable with the implant. The implant has an abutment head at one end and a threaded post projecting from the head and designed for threaded engagement in the jaw bone, the head having an outer locating surface portion. The retention member is generally cupshaped with a first end and a peripheral skirt extending from the first end to form a cavity, the skirt having an inner locating surface which is engaged over the outer locating surface portion of the head. The head may also have a socket in which a post extending from an inner end of the retention member engages as the parts are moved into releasable snap engagement.

RELATED APPLICATION

The present application claims the benefit of co-pending U.S.provisional patent application No. 61/091,982 filed Aug. 26, 2008, andco-pending U.S. provisional patent application No. 61/138,817 filed Dec.18, 2008, the contents of each of which are incorporated herein byreference in their entirety.

BACKGROUND

1. Field of the Invention

The present invention relates to an apparatus and method for anchoring adental appliance, and is particularly concerned with a mini orendosseous implant assembly and method.

2. Related Art

Various systems and methods are known for attaching a dental prosthesissuch as a full or partial denture or the like in a patient's jaw. Suchsystems generally comprise mating male and female parts, one of which isattached to the dental prosthesis and the other of which comprises anabutment which is mounted at a selected position in the patient's jaw.The abutment may be attached to a root, an endosseous implant, or anadjacent tooth, or in some cases may be inserted directly in the jawbone.

SUMMARY

Embodiments described herein provide for dental anchor apparatus havingan implant device with an abutment head for snap engagement with amating retention member engaged in a recess in a dental appliance, and athreaded post extending from the head for threaded engagement with bone.In one embodiment, the abutment head is formed integrally with the postto provide a one-piece endosseous implant. In alternative embodiments,the implant device is in two parts, comprising the abutment head and themain body of the implant, and the abutment head is releasably attachedto the main body.

According to one embodiment, a dental anchor apparatus comprises anendosseous implant securable in a patient's mouth and a retention memberwhich is releasably engageable with the implant. The implant has anabutment head at one end and a threaded post projecting from the headfor threaded engagement in bone, the head having at least an outerlocating surface portion. The retention member is generally cup-shapedwith a first end and a peripheral skirt extending from the first end toform a cavity, the skirt having an inner locating surface which isengaged over the outer locating surface portion of the head. Theretention member is designed for swivel engagement in a cap secured in arecess in a dental appliance.

In one embodiment, the inner locating surface of the skirt and the outerlocating surface portion of the head have interengageable snapformations and the retention member is releasably snap engaged over thehead. In another embodiment, the head has an inwardly extending socketwhich comprises a second locating portion and the retention member has apost extending from the first end inside the skirt which engages in thesocket when the retention member is snap engaged with the socket. Thepost may be used for alignment purposes. In one embodiment, the socketand post have interengageable snap formations to provide an inner snapengagement between the abutment and retention member. Both an inner snapengagement between the post and socket and an outer snap engagementbetween the cavity and outer locating portion of the head may beprovided in some embodiments, while in others only an inner or outersnap engagement is provided.

In some embodiments, the abutment head is formed integrally with theremainder of the body of the implant to provide a one-piece endosseousimplant, while in other embodiments the abutment head is formedseparately and releasably attached to the main body of the implant. Inthe latter case, the abutment head can be removed from the implant bodyand replaced with a new head when the locating surface portions becometoo worn to function properly, rather than replacing the entire implant.

In another embodiment, the outer locating surface on the head has afirst set of at least two axially spaced snap engaging formations whilethe inner locating surface of the retention member has a second set ofat least two axially spaced snap engaging formations for releasable snapengagement with the snap engaging formations on the head. One of thesets of snap engaging formations may comprises spaced annularprojections or ribs on one of the locating surfaces while the other setcomprises spaced annular grooves for snap engagement over the annularprojections or ribs. The post may be omitted in this embodiment, or thepost may be included for additional assistance in aligning the dentalappliance when placed in the mouth.

In one embodiment, the apparatus includes a cap which is secured in arecess in a dental appliance and which is designed to engage over theretention member, the cap and retention member having respective roundedinner and outer surfaces for swivel engagement of the retention memberin the cap. The swiveling engagement of the retention member in the capallows for a swiveling, rotational movement or hinging movement betweenthe cap and retention member. This allows minor corrections fornon-parallel abutments and reduces wear, as described in U.S. Pat. Nos.6,030,219 and 6,299,447, the contents of which are incorporated hereinby reference.

According to one embodiment, a two piece endosseous implant for a dentalattachment assembly comprises a main body having a first end portion anda threaded shaft extending from the first end portion for threadedengagement in the jaw bone, and an abutment head or member designed forremovable attachment to the main body of the implant. The abutmentmember has locating portion designed for releasable snap engagement withthe denture component or snap engaging part which is positioned in thedenture.

In a first embodiment of a two-piece endosseous implant, the first endportion of the main body has external threads which engage internalthreads in the abutment member or head. In an alternative embodiment,the abutment head has a shaft or post with external threads which engageinternal threads in a bore in the first end portion of the main body. Inboth of these alternatives, a tool may be provided for removal of theabutment head while holding the main body of the implant in place. Inone embodiment, the tool has a lower hex portion which engages in aninternal hex in the main body of the implant, while a driver portionwhich is rotatable relative to the lower hex portion engages with driveengaging portions in the locator or abutment head to unthread theabutment head from the main body. Alternatively, the abutment head andmain body may be designed with mating, taper press fit portions insteadof threaded engagement portions.

In both the one-piece and two-piece implants, the threaded post or shaftis adapted to be implanted directly in a prepared bore in a patient'sjaw bone, and may be designed for osseointegration with the patient'sjaw bone. The implant may be of so-called “mini-implant” dimensionshaving a maximum head diameter of the order of 1.5 mm. to 4.0 mm, andthe threaded post having a maximum thread diameter slightly less thanthe head diameter. The threaded post or shaft may be provided in a rangeof different lengths for selection based on the available implantationdepth in a patient's jaw bone. In one embodiment, the threaded post ofthe implant has a first portion of uniform outer diameter and a secondportion extending from the first portion to the end of the screw whichis of gradually tapered diameter. The threaded post may have a singlelead thread, a double lead thread, or other multiple lead threads, ordual threads of different pitch, and may have opposing axial cuts forself-tapping into a bone, so as to create threads in the bone as thethreaded post is engaged in a bore in the bone. A double, triple orquadruple lead thread allows for quick and solid engagement into atapped bone site. The projecting screw threads form an undercut regionand bone growth and attachment in this area increases the strength ofthe attachment and resistance to loosening forces.

In alternative embodiments, the threaded post may be designed foroptional later removal from the jaw bone for replacement purposes. Inthis case, the post may have a simple thread with no axial cuts. Insteadof the threaded post, other formations may be provided on the post forengagement with mating attachment formations in a prepared bore in thejaw bone or the like.

The implant may have a cuff area between the abutment head and post. Inthe case of a two-piece implant, the cuff area may be located entirelyon the first end portion of the main body, or entirely on the abutmenthead, or partly on the first end portion and partly on the head. In eachcase, different implants may be provided with cuff areas in differentheights to accommodate different tissue heights. The line of connectionor separation between the first end portion of the main body and theabutment head may be designed to be above the tissue or gum level, sothat the abutment head may be removed by a dentist without anydisturbance of the tissue.

Other features and advantages of the present invention will become morereadily apparent to those of ordinary skill in the art after reviewingthe following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The details of the present invention, both as to its structure andoperation, may be gleaned in part by study of the accompanying drawings,in which like reference numerals refer to like parts, and in which:

FIG. 1 is an enlarged view of a dental anchor apparatus according to afirst embodiment, with the parts of the apparatus separated;

FIG. 2 is an enlarged side elevation view of the dental anchor of FIG.1, with the parts assembled together;

FIG. 3 is a cross-sectional view of the apparatus on the lines 3-3 ofFIG. 2, on a smaller scale than in FIGS. 1 and 2, which illustrates theanchor assembly secured in a patient's jaw bone with the cap positionedin a denture or dental appliance;

FIG. 4 is an exploded sectional view of the circled portion of theapparatus in FIG. 3, illustrating the snap engagement between the headof the implant and the retention member;

FIG. 5 is a perspective view of the endosseous implant of the apparatusof FIGS. 1 to 4;

FIG. 6 is an enlarged top plan view of the implant of FIGS. 1 to 4;

FIG. 7 is an enlarged cross-sectional view of the retention member inthe anchor apparatus of FIGS. 1 to 6;

FIG. 8 is an enlarged side elevation view of an endosseous implantsimilar to the implant of FIGS. 1 to 7 but with a modified threaded postfor use in place of the post of FIGS. 1 to 7;

FIG. 9 is a cross-sectional view on the lines 9-9 of FIG. 8;

FIG. 10 is a side elevation view similar to FIG. 8 illustrating animplant with another modified threaded post for use in the apparatus ofFIGS. 1 to 7;

FIG. 11 is a side elevation view of another modified implant with amodified threaded post;

FIG. 12 is bottom plan view of the modified implant of FIG. 11, on asmaller scale than FIG. 11;

FIG. 13 is an exploded cross-sectional view of an anchor apparatussimilar to FIG. 1 but using the modified implant of FIGS. 11 and 12;

FIG. 14 is an enlarged view of the circled part of the anchor apparatusof FIG. 13 in an assembled condition;

FIG. 15 is an exploded side elevation view of another embodiment of ananchor apparatus;

FIG. 16 is a cross-sectional view of the dental anchor apparatus of FIG.15 with the parts assembled;

FIG. 17 is an enlarged sectional view of part of the retention member ofthe apparatus of FIGS. 15 and 16;

FIG. 18 is a perspective view of the implant of the apparatus of FIGS.15 and 16;

FIG. 19 is a top plan view of the implant of FIG. 18;

FIG. 20 is a side elevation view of an endosseous implant similar to theimplant in the apparatus of FIGS. 15 to 19 but with a modified threadedpost;

FIG. 21 is a side elevation view of an implant similar to the implant ofFIG. 20 but with another modified threaded post;

FIG. 22 is an exploded side elevation view of a dental anchor apparatusaccording to another embodiment;

FIG. 23 is a side elevation view of the dental anchor apparatus of FIG.22 with the parts assembled;

FIG. 24 is a cross-sectional view on the lines 23-23 of FIG. 23;

FIG. 25 is a side elevation view of an endosseous implant similar to theimplant in the apparatus of FIGS. 22 to 24 but with a modified threadedpost;

FIG. 26 is a side elevation view of an implant similar to the implant ofFIG. 25 but with a modified threaded post;

FIG. 27 is an exploded side elevation view of a two part mini implantaccording to another embodiment, with the parts of the implantseparated;

FIG. 28 is a longitudinal cross sectional view of the two part miniimplant of FIG. 27 on the lines 28-28 of FIG. 27;

FIG. 28A is a top plan view of the abutment head of the two part implantof FIGS. 27 and 28;

FIG. 29 is a top plan view of the main body of the implant of FIGS. 27and 28, illustrating the internal hex;

FIG. 30 is a bottom plan view of the main body of the implant of FIGS.27 and 28;

FIG. 31 is a side elevation view illustrating the two parts of the miniimplant or attachment member of FIGS. 27 to 30 secured together and inuse and in releasable snap engagement with a male or retention memberwhich is in swivel engagement in a cap positioned in a denture or dentalappliance;

FIG. 32 is a longitudinal cross sectional view of the dental anchorapparatus of FIG. 31 on the lines 32-32 of FIG. 31, schematicallyindicating the endosseous hard bone level, soft tissue area, and thearea above the surrounding tissue when the assembly is in use;

FIG. 33 is a perspective view of a driver or removal tool for separatingthe abutment head from the main body of the implant of FIGS. 27 to 32when needed for repair or replacement purposes;

FIG. 34 is a longitudinal cross sectional view of the removal tool ofFIG. 33;

FIG. 34A is a perspective view of the triangle driver of the removaltool of FIGS. 33 and 34;

FIG. 35 is an exploded side elevation view of a two part mini implantaccording to another embodiment, with the parts of the implantseparated;

FIG. 36 is a longitudinal cross-sectional view of the abutment head ofthe mini implant of FIG. 35;

FIG. 37 is a top plan view of the abutment head of FIG. 36;

FIG. 38 is a longitudinal cross-sectional view of the internallythreaded main body of the implant of FIG. 35;

FIG. 39 is an exploded side elevation view of a modified two part miniimplant according to another embodiment, which is similar to theinternal thread attachment implant of FIGS. 33 to 38 but with the lineof separation between the two parts at a different location;

FIG. 40 is a vertical cross-sectional view on the lines 40-40 of FIG.39;

FIG. 41 is an exploded side elevation view of a taper press fit two partmini implant according to another embodiment, with the parts of theimplant separated;

FIG. 42 is a cross-sectional view of the implant parts on the line 42-42of FIG. 41;

FIG. 43 is a top plan view of the abutment head of the two part implantof FIGS. 41 and 42; and

FIG. 44 is a bottom plan view of the abutment head of FIG. 43

FIG. 45 is an exploded side elevation view of another modified two partmini implant according to another embodiment, with the parts of theimplant separated;

FIG. 46 is a longitudinal cross-sectional view of the parts on the line46-46 of FIG. 45;

FIG. 47 is a perspective view of the main body of the implant of FIGS.45 and 46, illustrating the external, tool engaging hexagonal formation;

FIG. 48 is a side elevation view of the assembled parts of a dentalanchor apparatus including the two part implant of FIGS. 45 to 47; and

FIG. 49 is a longitudinal cross-sectional view on the lines 49-49 ofFIG. 48.

DETAILED DESCRIPTION

Certain embodiments as disclosed herein provide for a dental attachmentor anchor apparatus having an endosseous implant which has an abutmenthead and a post extending from the head for direct engagement in apatient's jaw bone, and a retention member designed for snap engagementover the head of the implant and for swivel engagement in a cap securedin a dental appliance or prosthesis. The retention member and implanthave interengageable snap engagement formations for releasably retainingthe dental appliance or prosthesis on the implant member. In aninstallation, a plurality of spaced implants are implanted in the jawbone and retention members engaged in correspondingly spaced capssecured in the dental appliance are snap engaged with the abutment headsof the respective implants to retain the dental appliance in position ina patient's mouth.

After reading this description it will become apparent to one skilled inthe art how to implement the invention in various alternativeembodiments and alternative applications. However, although variousembodiments of the present invention will be described herein, it isunderstood that these embodiments are presented by way of example only,and not limitation. As such, this detailed description of variousalternative embodiments should not be construed to limit the scope orbreadth of the present invention.

In the following description, the terms “upper” and “lower” are used todenote locations of various portions of the implant as seen in thedrawings, and are not intended to indicate which ends are uppermost whenthe implant is installed in the jaw, which is dependent on whether theimplant is located in the upper or lower jaw.

FIGS. 1 to 7 illustrate a first embodiment of a dental attachment oranchor apparatus 10 comprising a one-piece implant 12 with an abutmenthead or head portion 20 and an integral threaded post or shaft 14, aretention member 15 for releasable snap engagement with the head 20 ofimplant 12, and a cap 16 designed to be secured in an indent in a dentalappliance 18 such as an overdenture, a partial denture, or the like, asillustrated in FIG. 3. Implant 12 is of relatively strong material suchas coated titanium or other standard materials generally used for dentalanchors or abutments, and the threaded post 14 is designed for directengagement in a prepared bore in endosseous bone 100, as indicated inFIG. 3.

Head 20 has a generally flat first end 22, and an outer curved orbulbous locating portion 23 extending from first end. A generallycylindrical portion or cuff portion 24 extends from the end of locatingportion 23, and an inwardly tapered rim portion 25 extends from firstcylindrical portion 24. Implants may be made with cuff portions ofdifferent heights to accommodate patients with different tissue heights.In this embodiment, threaded post or shaft 14 has a short cylindricalportion 26 extending from rim portion 25, and single thread 28 extendingalong the remainder of the length of the post or shaft 14. Post 14 hasan inwardly tapered end portion 30 extending up to the tip 32 of thepost.

FIGS. 2 to 4 illustrate the parts of FIG. 1 assembled together, with theretention member 15 in hinging, snap engagement in cap 16 and releasablysnap engaged over the locating portion 23 of head 20. FIG. 3 illustratesthe operative condition of the parts, with cap 16 installed in asuitable cavity in a dental appliance or prosthesis 18, and the threadedpost 14 in threaded engagement in a prepared bore in jaw bone 100. Thethreaded post may be coated by any suitable coating material prior toinstallation, as is known in the field of endosseous implants.

As illustrated in FIGS. 3 to 6, the head 20 of implant 12 has a socket34 extending from flat end face 22 through part of the length of thehead, and has an inwardly extending rounded rim 35 at the outer end ofthe socket. Rim 35 has cut-outs 36, as seen in FIGS. 4 and 5, forreceiving the end of a suitable tool for securing the threaded post in aprepared bore in a patient's jaw bone. One or more weep holes 37 areprovided through the wall of the socket, as seen in FIG. 4, to allowsaliva to escape from the socket.

As best illustrated in FIG. 7, the retention member 15 is generallycup-shaped with a generally flat first end 38, an outer skirt 39extending from first end 38 defining an internal cavity 40 forengagement over the head 20, and a retention pin or post 42 extendingfrom end 38 inside the cavity for engagement in socket 34, as seen inFIGS. 3 and 4. Retention member 15 is made of a material having someresilience, such as nylon or plastic material. Retention member 15 maybe similar to the retention or male elements as described in U.S. Pat.Nos. 6,030,219 and 6,299,447 of Zuest et al., the contents of which areincorporated herein by reference. The skirt 39 has a concave innersurface or locating portion 44 designed for snap engagement over theouter locating portion. The retention pin or post 42 has an enlarged endportion 45 (FIG. 4) of slightly larger diameter than the remainder ofthe post, and slightly smaller diameter than the inner diameter ofsocket rim 35, with the rim 35 and end portion 45 comprising snapengaging formations. As the skirt 39 engages over outer locating portion23 of the head, the end of post 42 is compressed slightly as it isforced through the opening defined by socket rim 35, and then expands sothat it is releasably retained in the socket. Similarly, the outer endof skirt 38 is expanded as it is forced over the bulbous or roundedsurface of locating portion 23, then snaps back to engage the end oflocating portion 23. Thus, the locating portion 23 and inner concavesurface of skirt 38 comprise a second set of snap engaging formationsbetween the retention member 15 and the head 20 of abutment member 12.

The outer surface 46 of the retention member 15 is convex or rounded forsnap-fit, swiveling engagement in a cavity 48 of corresponding shape inthe cap 16, as illustrated in FIGS. 3 and 4. The swivel joint formedbetween the retention member and cap is similar or identical to thatdescribed in U.S. Pat. Nos. 6,030,219 and 6,299,447 referenced above.The pivoting of the nylon or plastic resilient retention or male member15 in the metal denture cap 16 allows minor corrections for non parallelabutments as well as providing a longer lasting, resilient connection.

In one embodiment, the anchor apparatus is made in a range of differentsizes for selection by a dental surgeon or dentist based on the size ofa patient's jaw and the available tissue and bone depth and thickness.The implant or abutment member may be provided in a similar size rangeto so-called mini abutment members or mini implants. In one embodiment,heads 20 are provided in a range of diameters from around 1.5 mm. to 4.0mm., while the length of the threaded post may be in the range fromaround 6 mm. to 21 mm. A plurality of mini abutment members 12 aresecured at selected locations in the jaw bone, depending on the size ofthe dental appliance to be secured, and caps 16 are secured atcorresponding locations in the dental appliance. Male or retentionmembers 15 are engaged in the respective caps, and the dental appliancecan then be readily secured in the jaw by snap engaging the respectiveretention members over the opposing heads 20 of the abutment members.

The pitch or angle of the thread may be relatively steep and is in therange from around 9° to 17° in one embodiment. The spacing betweenadjacent threads is preferably at least 1 mm. It has been found thatthis is the minimum spacing required to ensure significant bone growthand osseointegration in the gaps between threads. The threads mayproject out around ½ mm from the surface of the shaft portion of theimplant, and they are about ½ mm in height.

FIGS. 8 and 9 illustrate a modified implant 50 which may be used inplace of the implant 12 in the anchor apparatus of FIGS. 1 to 7. Implant50 has a modified threaded post 52. Other parts of the implant 50,particularly the head 20, are identical to corresponding parts in FIGS.1 to 7, and like reference numbers have been used as appropriate.Threaded post 52 is shorter than post 14 of the previous embodiment andhas a longer lead-in portion 54 which is unthreaded. Post 52 is slightlytapered along threaded portion 55 and has a flat end 56.

FIG. 10 illustrates another modified implant 60 which may replaceimplant 12 of FIGS. 1 to 7. Implant 60 also has an abutment head 20substantially identical to that of implant 12, but has a modifiedthreaded shaft 62 which has no unthreaded lead in portion, and insteadhas micro-threads 64 in an upper portion of the shaft, followed by adouble lead thread 63 along the lower portion 65 of the shaft with twothreads offset by 180 degrees. Double lead threads will screw in twiceas fast as a single lead thread. Bone grows into micro-threads fasterand more effectively than larger threads, so this arrangement helps toanchor the implant and resists loosening.

FIGS. 11 and 12 illustrate a modified implant 70 which has similarthreads in the threaded shaft 72 to implant 60, and like referencenumbers are used as appropriate. However, the threaded shaft 72 also hastwo diametrically opposed, axially extending flats 74 for self-tappingpurposes. The flats also help to resist unthreading of the implant afterimplantation. Implant 70 is otherwise identical to implant 60, and likereferences numbers are used for like parts as appropriate. FIGS. 13 and14 illustrate implant 70 together with the retention member 15 and cap16 of FIGS. 1 to 7.

FIGS. 15 to 19 illustrate a dental anchor apparatus 80 according toanother embodiment comprising a one-piece implant 82, a retention member84, and a cap 85 designed to be secured in a recess or indent providedin a dental appliance such as a denture, partial denture, or the like.Implant 82 is similar to the implant of FIGS. 1 to 7 in some respects,and like reference numbers are used for like parts as appropriate, buthas a shorter abutment head 86 and an integral threaded post or shaft 14which is similar or identical to shaft 14 of FIGS. 1 to 7 apart fromdimensional variations. The retention member 84 and cap 85 are alsosimilar to retention member 15 and cap 16 of the first embodiment, andlike reference numbers are used for like parts as appropriate. However,these parts are shorter in length than the corresponding parts of anchorapparatus 10, so that the overall height of the apparatus is reduced.Implant 82 is of relatively strong material such as coated titanium orother standard materials generally used for dental anchors or abutments,and the threaded post 14 is designed for direct engagement in a preparedbore in endosseous bone 100, in the same manner as indicated in FIG. 3for the first embodiment.

As in the first embodiment, abutment head 86 has a generally flat firstend 22, and an outer curved or bulbous locating portion 23 extendingfrom first end. A shortened cylindrical portion 88 extends from the endof locating portion 23, and an inwardly tapered rim portion 89 extendsfrom cylindrical portion 88 up to the non-threaded end portion 26 ofthreaded post or shaft 14. FIG. 16 illustrates the parts of FIG. 15assembled together. As illustrated in FIG. 16, retention member 84 is inhinging, snap engagement in cap 85 and is releasably snap engaged overthe locating portion 23 of head 86. The threaded post may be coated byany suitable coating material prior to installation, as is known in thefield of endosseous implants.

As illustrated in FIGS. 16 and 18, and as in the previous embodiments,the head 86 of implant 82 has a socket 34 extending from flat end face22 through part of the length of the head, and has an inwardly extendingrounded rim 35 at the outer end of the socket. Rim 35 has cut-outs 36,as seen in FIGS. 18 and 19, for receiving the end of a suitable tool forsecuring the threaded post in a prepared bore in a patient's jaw bone.One or more weep holes 37 are provided through the wall of the socket toallow saliva to escape from the socket.

As illustrated in FIGS. 16 and 17, the retention member 84 is of similarcup-like shape to the previous embodiments, but shorter in length, witha generally flat first end 38, an outer skirt 39 extending from firstend 38 defining an internal cavity 40 for engagement over the head 20,and a retention pin or post 42 extending from end 38 inside the cavityfor engagement in socket 34, as seen in FIGS. 16 and 17. Retentionmember 84 is made of a material having some resilience, such as nylon,plastic, rubber, or rubber-like material. Retention member 84 may besimilar to the retention or male elements as described in U.S. Pat. Nos.6,030,219 and 6,299,447 of Zuest et al., the contents of which areincorporated herein by reference. As in the previous embodiments, theskirt 39 has a concave inner surface or locating portion 44 designed forsnap engagement over the outer locating portion 23 of head 86. Theretention pin or post 42 has an enlarged end portion 45 (FIG. 17) ofslightly larger diameter than the remainder of the post, and slightlysmaller diameter than the inner diameter of socket rim 35, with the rim35 and end portion 45 comprising inner snap engaging formations. As theskirt 39 engages over outer locating portion 23 of the head, the end ofpost 42 is compressed slightly as it is forced through the openingdefined by socket rim 35, and then expands so that it is releasablyretained in the socket. Similarly, the outer end of skirt 38 is expandedas it is forced over the bulbous or rounded surface of locating portion23, then snaps back to engage the end of locating portion 23. Thus, thelocating portion 23 and inner concave surface of skirt 38 comprise asecond set of snap engaging formations between the retention member 84and the head 86 of implant 82.

The outer surface 46 of the retention member 84 is convex or rounded forsnap-fit, swiveling engagement in a cavity 48 of corresponding shape inthe cap 85, as in the previous embodiments, and as illustrated in FIG.16. The swivel joint formed between the retention member and cap issimilar or identical to that described in U.S. Pat. Nos. 6,030,219 and6,299,447 referenced above. The pivoting of the nylon or plasticresilient retention or male member 84 in the metal denture cap 85 allowsminor corrections for non parallel abutments as well as providing alonger lasting, resilient connection.

FIG. 20 illustrates a modified implant 95 which may be used in place ofthe implant 82 in the anchor apparatus of FIGS. 15 to 19. Implant 95 hasan identical abutment head 86 to implant 82, but the threaded post 14 isreplaced by a modified threaded post 62 which is identical to thethreaded post illustrated and described above in connection with FIG.10, and like reference numbers are used for like parts as appropriate.FIG. 21 illustrates another modified implant 96 which may replaceimplant 82 of FIGS. 15 to 19. Implant 96 also has a head 86substantially identical to that of implant 82, but has a modifiedthreaded shaft 72 identical to the shaft of the implant 70 of FIGS. 11to 14, and like reference numbers are used for like parts asappropriate.

FIGS. 22 to 24 illustrate a dental anchor apparatus 100 according toanother embodiment comprising a one-piece endosseous implant 102, aretention member 104, and a cap 105 designed to be secured in a recessor indent provided in a dental appliance such as a denture, partialdenture, or the like. Implant 102 has a modified abutment head 106 andan integral threaded post or shaft 14 which is similar to the threadedshaft of the implant of FIGS. 1 to 7, and like reference numbers areused for like parts as appropriate. As in the previous embodiments,implant 102 is of relatively strong material such as coated titanium orother standard materials generally used for dental anchors or abutments,and the threaded post 14 is designed for direct engagement in a preparedbore in endosseous bone 100, in the same manner as indicated in FIG. 3for the first embodiment. The threaded post may be coated by anysuitable coating material prior to installation, as is known in thefield of endosseous implants.

Retention member 104 is of a material having some resilience, such asnylon or plastic material, as in the previous embodiments. Retentionmember 104 may be similar or identical to the retention or female memberdescribed in U.S. Pat. No. 6,981,871 of Mullaly et al., the contents ofwhich are incorporated herein by reference, while head 106 of theimplant 102 is similar to the head of the device described in U.S. Pat.No. 6,981,871 to provide a similar outer snap engagement mechanism.

Head 106 has a first end 108, and an outer locating surface projectingaway from the first end which has at least two axially spaced retentionor snap engagement portions 110, 112 which comprise annular retentionribs separated by an annular groove 114. In the illustrated embodiment,the first rib or retention portion 110 is of smaller diameter than thesecond rib or retention portion 112, although they may be of the samediameter in other embodiments. A cylindrical portion 115 extends fromrib 112 and terminates in a tapered portion 116 transitioning to thenon-threaded end portion 26 of threaded post 14. As in the previousembodiments, a socket 118 extends inwardly from the end 108 of the head,with cut outs around the rim for receiving a tool used for screwing thepost 14 into a prepared bore in endosseous bone. However, in this case,the retention member 104 does not have any post which is in snapengagement in bore 118, since an external snap engagement only isprovided, as explained in more detail below. In alternative embodiments,an inner snap engagement may also be provided between retention member104 and the head of implant 102 in a similar manner to the previousembodiments. One or more weep holes (not illustrated) may be providedthrough the wall of the socket 118 to allow saliva to escape from thesocket.

As illustrated in FIG. 24, retention member 104 is of generally cup-likeshape having a first end 120 and a skirt 122 projecting from the firstend for snap engagement over the locating or retention portions of head106. As noted above, retention member 104 is similar or identical to theretention member described in U.S. Pat. No. 6,981,871 referenced above.The outer surface 124 of skirt 122 is arcuate and designed for swivelengagement in cap 105, as seen in FIG. 24.

The inner surface of skirt 122 has a projecting annular rib 125separating the cavity into first and second annular indented regions orrounded grooves 126, 128 for snap engagement over ribs 110, 112. Asillustrated in FIG. 24, when the parts are assembled together, retentionmember 104 is in hinging, snap engagement in cap 105 and is releasablysnap engaged over the locating portions of head 106. The swivel jointformed between the retention member and cap is similar or identical tothat described in U.S. Pat. Nos. 6,030,219, 6,299,447, and 6,981,871referenced above. The pivoting of the nylon or plastic resilientretention member 104 in the metal denture cap 105 allows minorcorrections for non parallel abutments as well as providing a longerlasting, resilient connection. At the same time, the retention member isheld securely in the cap as the patient removes and replaces the dentalappliance.

FIG. 25 illustrates a modified implant 130 which may be used in place ofthe implant 102 in the anchor apparatus of FIGS. 22 to 24. Implant 130has an identical abutment head 106 to implant 102, but the threaded post14 is replaced by a modified threaded post 62 which is identical to thethreaded post illustrated and described above in connection with FIG.10, and like reference numbers are used for like parts as appropriate.FIG. 26 illustrates another modified implant 135 which may replaceimplant 102 of FIGS. 22 to 24. Implant 135 also has a head 106substantially identical to that of implant 102, but has a modifiedthreaded shaft 72 identical to the shaft of the implant 70 of FIGS. 11to 14, and like reference numbers are used for like parts asappropriate.

In each of the above embodiments, an implant with an integral abutmenthead designed for snap engagement with a retention member retained in acap in a dental prosthesis can be directly implanted into a preparedbore in the jawbone, expediting delivery of a finished denture, partialdenture, or other dental prosthesis to a patient. Two or more suchimplants are placed at selected locations in a patient's mouth,depending on the size and location of the dental prosthesis to beinstalled. Bores are first prepared at suitable locations in the jawbone, and the threaded shafts of the selected implants are threaded intothe bores. As noted above, the shafts or posts may first be treated withsuitable coating and/or adhesive materials. Once installed, the locatingportions of the integral abutment heads project above the bone and thegum level for snap engagement in opposing retention members which are inswivel engagement with caps secured in the dental appliance. Theresilient nylon or plastic retention members remain in static engagementwith the integral heads of the implant when the appliance is in place,while the metal caps have a full range of rotational or swivel movementover the retention members while the dental appliance is in use, and cancompensate for any misalignment between implants. At the same time, thewearer can readily remove the appliance by snapping the retentionmembers off the heads of the implants as necessary for cleaningpurposes, and can easily replace the appliance by urging the retentionmembers onto the heads of the aligned implants until they snap intoplace.

FIGS. 27 to 32 illustrate a dental attachment or anchor apparatus 200according to another embodiment comprising an implant 210, a retentionmember 250, and a cap 252 which is similar to cap 16 of the previousembodiments. The implant 210 is shown separate from the other parts inFIGS. 27 to 30, while all of the parts are shown assembled together inFIGS. 31 and 32, as described in more detail below. In this embodiment,the one-piece implant of the previous embodiments is replaced with atwo-piece implant 210 comprising a main body 212 with a first endportion 220 at a first end of the body and an integral threaded post orshaft 214 extending from the end portion 220, and a separate abutmenthead or member 215 which is removably securable to the main body. FIGS.27 and 28 illustrate the two parts of the implant 210 separated from oneanother, while FIGS. 31 and 32 illustrate the abutment head 215 securedto the first end portion 220 of the main body, along with retentionmember 250 snap engaged with outer and inner locating portions of theabutment head, and in swivel engagement in a cap 252 designed to besecured in an indent in a dental appliance 254 such as an overdenture, apartial denture, or the like. The two piece implant 210 is of relativelystrong material such as coated titanium or other standard materialsgenerally used for dental anchors or abutments, for example titaniumwith a coating layer of titanium nitride on the attachment or locatorsurfaces of abutment member 215. In one embodiment, the threaded post214 is designed for direct engagement in a prepared bore in endosseousbone 256, as indicated in FIG. 32.

In the embodiment of FIGS. 27 to 32, the first end portion 220 of themain body 212 has an external thread which connects the two parts of theimplant together. The first end portion 220 of body 212 comprisesannular cuff portion 222 and an externally threaded projection or boss224 extending from one end of cuff portion 222. Threaded stem or post214 extends from the other end of cuff portion 222, which has a curved,tapered lead-in 221 to the reduced diameter post 214. As bestillustrated in FIGS. 28 and 29, a hexagonal, tool-receiving bore 225extends inwardly from the upper end of threaded projection 224. Anannular seat or beveled cup portion 226 with a recessed, inwardlytapered bevel or rim 228 surrounds projection 224 at the upper end ofcuff portion 222, as best illustrated in FIG. 28.

Abutment head or member 215 has a through bore with a threaded lower endportion 230 which is designed for releasable threaded engagement withthe external threads on projection or boss 224 at the upper end of themain body 212. The upper or first end of the through bore comprises asocket 232 with an inwardly projecting, bulbous peripheral rim 233 forreleasable snap engagement with the end of a post 234 of retentionmember 250 located in a denture or dental appliance, as illustrated inFIGS. 31 and 32 and described in more detail below. The peripheral rim233 has three indents 231 in a triangular pattern for engaging a removaltool, as illustrated in FIG. 28A and as described in more detail belowin connection with FIGS. 33, 34, and 34A. The abutment head has a first,convex or bulbous locating portion 236 extending from the flat upper orfirst end of the member, a cylindrical waist portion 237 extending fromend portion 235, an outer annular rim 238 connected to the waist portionby outwardly tapered portion 240, and an inwardly tapered or bevelportion 242 extending from the waist portion to the flat lower end ofthe member 215. Annular rim 238 forms part of the cuff of the implantwhen the parts are secured together, as seen in FIGS. 31 and 32. One ormore weep holes 244 may be provided through the wall of the socket, asseen in FIG. 27, to allow saliva to escape from the socket. The taperand dimensions of lower bevel portion 242 match those of the inner bevel228 at the upper end of the main body.

FIGS. 31 and 32 illustrates the two parts of FIGS. 27 and 28 assembledtogether, with the abutment head 215 in threaded engagement over thethreaded projection 224 and the lower bevel 242 engaging inner bevel 228of seat 226 in the upper or first end portion of the main body. Theseating of the lower end of the abutment head 215 in the upper beveledcup portion 226 of the main body, along with the engagement of thebeveled lower end face 242 against the corresponding beveled rim 228 ofthe cup portion 226, helps to reduce lateral stress on the threadconnecting the two parts.

In FIGS. 31 and 32, the two part mini implant is shown in use and inreleasable snap engagement with a cap male or retention member 250 whichis in swivel engagement in a cap 252 secured in a recess in a denture ordental appliance 254, part of which is schematically illustrated in FIG.32. FIG. 32 also schematically illustrates the tissue or gum 255surrounding the implant and hard or endosseous bone 256 in whichthreaded post 214 is embedded, and the approximate location of theattachment parts relative to the bone and tissue level. The outerseparation line 260 between the two parts of the implant 210 is locatedalong the height of the cuff region and slightly below the tissue levelwhen the implant is installed, as seen in FIGS. 31 and 32.

In FIGS. 31 and 32, the retention member 250 is in hinging, snapengagement in cap 252 and releasably snap engaged over the outerlocating surface portion 236 of abutment head 215. At the same time,post or shaft 234 is in snap engagement in socket 232. FIG. 32schematically illustrates the operative condition of the parts, with cap252 installed in a suitable cavity in a dental appliance or prosthesis254, and the threaded post 214 in threaded engagement in a prepared borein jaw bone 256. The threaded post may be coated by any suitable coatingmaterial prior to installation, as is known in the field of endosseousimplants.

Retention member 250 may be similar to the retention or male elements asdescribed in U.S. Pat. Nos. 6,030,219 and 6,299,447 of Zuest et al., thecontents of which are incorporated herein by reference, and may be amale or retention member as sold by Zest Anchors of Escondido, Calif.under the name Locator®. In alternative embodiments, the abutment membermay be designed for releasable snap engagement with other types of maleor retention members as used in dentures, while attaching to the mainbody of the implant in the same way as indicated in the drawings. Theretention member 250 of FIGS. 31 and 32 has a skirt 258 with a concaveinner surface or locating portion designed for snap engagement over theouter locating portion 236 of the abutment member. The retention pin orpost 234 has an enlarged end portion of slightly larger diameter thanthe remainder of the post, and slightly smaller diameter than the innerdiameter of socket rim 233, with the rim 233 and the end portion of post234 comprising snap engaging formations. As the skirt engages over outerlocating portion 232 of the head, the end of post 234 is compressedslightly as it is forced through the opening defined by socket rim 233,and then expands so that it is releasably retained in the socket.Similarly, the outer end of skirt 258 is expanded as it is forced overthe bulbous or rounded surface of locating portion 232, then snaps backto engage over the end of locating portion 232 against the reduceddiameter waist portion 237, as seen in FIG. 32. The outer surface of theretention member 250 is convex or rounded for snap-fit, swivelingengagement in a cavity of corresponding shape in the cap 252, asillustrated in FIG. 32, with the small gap between the opposing innerends of cap 252 and retention member 250 allowing a small degree ofswivel. The swivel joint formed between the retention member and cap issimilar or identical to that described in U.S. Pat. Nos. 6,030,219 and6,299,447 referenced above. The pivoting of the nylon or plasticresilient retention or male member 250 in the metal denture cap 252allows minor corrections for non parallel abutments as well as providinga longer lasting, resilient connection.

The two piece implant may be made in a range of different sizes forselection by a dental surgeon or dentist based on the size of apatient's jaw and the available tissue and bone depth and thickness. Thetwo piece implant 210 may be provided in a similar size range toso-called mini abutment members or mini implants. In one embodiment,abutment members 215 are provided in a range of diameters from around1.5 mm. to 4.0 mm., while the length of the threaded post 214 may be inthe range from around 6 mm. to 21 mm. A plurality of two piece implantsare secured at selected locations in the jaw bone, depending on the sizeof the dental appliance to be secured, and caps 252 are secured atcorresponding locations in the dental appliance. Male or retentionmembers 250 are engaged in the respective caps, and the dental appliancecan then be readily secured in the jaw by snap engaging the respectiveretention members over the opposing ends or locating portions of theabutment heads 215.

In one embodiment, the threads on the shaft or post 214 of the main bodymay be designed to allow bone growth and osseointegration. In theillustrated embodiment, the threads are designed for bone growth and thepitch or angle of the thread on the shaft or post 214 of the main bodyis relatively steep and may be in the range from around 9° to 17°. Thespacing between adjacent threads may be at least 1 mm. It has been foundthat this is the minimum spacing allowing significant bone growth andosseointegration in the gaps between threads. In one embodiment, thethreads project out around ½ mm from the surface of the shaft portion ofthe implant, and are about ½ mm in height. The thread design may besimilar or identical to that described above in connection with theone-piece implants of FIGS. 1 to 26. In the embodiment of FIGS. 27 to32, the shaft has an unthreaded lead in portion 262 followed by amicro-threaded portion 264, and a double lead thread 265 along the lowerportion of the shaft. Double lead threads will screw in twice as fast asa single lead thread. Bone grows into micro-threads faster and moreeffectively than larger threads, so this arrangement helps to anchor theimplant and resists loosening. In the illustrated embodiment, thethreaded portion of shaft 214 also has two diametrically opposed,axially extending flats 268 for self-tapping purposes. The flats alsohelp to resist unthreading of the implant member after implantation.Other thread designs may be used in alternative embodiments. In theillustrated embodiment, shaft 214 is tapered along at least part of itslength up to tip 267, but may be of uniform diameter in otherembodiments. Alternative thread or other bone integration formations maybe used in other embodiments.

By making the mini implant in two pieces rather than one, the upperabutment head or member 215 can be replaced while leaving the main bodyof the implant in place in the jaw bone, which is an advantage over aone piece implant which would have to be completely removed and replacedor altered to continue proper usage when the attachment or locatingsurfaces become worn. In the embodiment of FIGS. 27 to 32, the abutmentmember 215 can be removed from the main body by the dentist byunscrewing it from the externally threaded boss or post 224 at the upperend of the main body 212 of the implant. FIGS. 33, 34 and 34A illustrateone embodiment of a removal tool 270 which may be used to remove theabutment member 215 from the main body 212 of the two piece implant ifthe retention or snap engagement surfaces become worn, requiringreplacement of member 215. The removal tool has a central shaft 271 anda triangle driver or sleeve 272 rotatably mounted over a central regionof the shaft, as seen in FIG. 34. Shaft 271 has a generally cylindricalcentral portion 274 on which the driver 272 rotates, a hexagonal wrenchholding portion 275 at one end, and a smaller hexagonal portion 276 atthe opposite end designed to engage in the hexagonal bore 225 at theupper end of the main body 212. Triangle driver 272 is illustratedseparately in FIG. 34A and comprises a sleeve member having a centralcylindrical through bore 273 rotatably engaged over central portion 274of the shaft, a first, larger end portion or gripping portion 278 ofhexagonal shape, and a drive portion 280 which has three spaced ears orribs 282 arranged in triangle and designed to engage in the triangulararrangement of indents or notches 231 in the inner rim 233 of the socket232 in abutment member 215.

In order to remove the abutment head 215, the lower hex portion 276 ofthe removal tool is engaged in the internal hex 225 of the main body ofthe implant to hold it in place and protect it from unthreading stress.The driver portion 280 of the triangle driver 272 is engaged in thesocket 232 of the abutment head 215 with the ears or ribs 282 engagingin notches 231, and is then rotated to unthread the abutment member head215 from threaded post or boss 224 while the lower hex portion 276 ofthe shaft holds the main body stationary. The lower hex portion 276 mayalso be used for threading the main body 212 into a prepared bore in thejaw bone on original installation of the implant.

FIGS. 35 to 38 illustrate a two piece mini implant 290 according to asecond embodiment, in which the external threaded attachment to the mainbody of the implant is replaced with an internal threaded attachment.The mini implant 290 comprises a main body 292 with an enlarged firstend portion 294 at a first end of the body and an integral threaded postor shaft 295 extending from the first end portion, and a separateabutment head 296 which is removably securable to the main body. Theimplant is of identical or similar materials to the previous embodiment.The external threaded arrangement of the shaft 295 is identical to theprevious embodiment, and like reference numerals are used for likeportions of the shaft as appropriate.

The first end portion 294 comprises a cylindrical cuff portion similarto that of the previous embodiment, with a cup shaped seat 298 having abeveled outer rim 299 and a bore 300 extending from the seat into theshaft portion of the main body having a hex portion 302 at its upper end(see FIG. 38). Bore 300 is longer than in the previous embodiment andhas a threaded inner end portion 304. The abutment head 296 has an endportion 305 of similar external shape to abutment head 215, with asimilar upper end socket 232 to the previous embodiment, and likereference numbers have been used for like parts as appropriate. However,instead of a threaded bore as in the previous embodiment, the abutmenthead 296 of this embodiment has a shaft 306 which extends from portion305 and has a threaded portion 308 for threaded engagement in thethreaded inner end portion 304 of the bore in main body 292. Thus, inthis embodiment, an internal thread connects the two parts of the miniimplant. The abutment head 215 may be removed for replacement if neededby unthreading it from the main body, using a triangle driver similar tothe triangle driver of tool 270 illustrated in FIG. 34A.

As in the previous embodiment, the lower beveled portion 242 of endportion 305 of abutment head 296 is seated in cup-shaped seat 298 at theupper end of the main body when the parts are secured together via theinternal thread attachment, with the lower beveled face 242 of theabutment head engaging the beveled rim 299 of seat 298. This helps toreduce lateral stress on the smaller thread 308, 304 which connects thetwo parts.

Once installed in the jaw, the two piece implant 290 functions inexactly the same way as described above in connection with the previousembodiment, with a male or retention member 250 snap engaging over theupper end of head portion 305 with its post 234 in snap engagement insocket 232, as described above in connection with FIGS. 31 and 32. Aplurality of two piece mini implants 290 can therefore be used toreleasably attach a denture or dental appliance in a patient's mouth,using standard male or retention members in swivel engagement inappropriately placed caps 252 in the appliance.

FIGS. 39 and 40 illustrate another embodiment of a two piece implant 310which has an internal threaded attachment between the parts, as in theprevious embodiment. The implant 310 is similar to the implant 290 ofthe previous embodiment, and like reference numbers have been used forlike parts as appropriate. However, in this embodiment, the enlargedlower part of the end portion of the abutment head is removed, and thehead portion of the main body has a taller cuff area, while the line ofattachment between the parts is higher than in the previous twoembodiments, as described in more detail below.

As illustrated in FIGS. 39 and 40, implant 310 comprises a main body 312which is designed to be implanted in a patient's jaw in the mannerdescribed above in connection with the first embodiment, and an abutmenthead 314 designed for releasable attachment to the main body via athreaded shaft 306 which engages a threaded inner end portion 304 of thebore 300 in main body 312, in a similar manner to that described abovein connection with FIGS. 36 to 38. The main difference between the mainbody 312 of this embodiment and the main body of the previous embodimentis that body 312 has a head or end portion with a longer outer cuffportion 315, and the upper end has an outer bevel 316 which surroundsthe beveled inner rim 299 of the upper cup shaped seat 298. Main body312 is otherwise identical to main body 292 of the previous embodiment,and like references have been used for like parts as noted above.

The part of the cuff region which was provided on the abutment head inthe previous embodiments (i.e. outer annular region 238 along with theupper tapered portion 240) is eliminated from the abutment head in thisembodiment, and instead the entire cuff portion 315 is located on thehead of the main body, along with the upper bevel 316 which correspondsto bevel 240 in the previous two embodiments. The abutment head 314 inthis embodiment therefore has an end portion which terminates with anannular, downwardly facing bevel 320 at the lower end of waist orindented portion 237 which corresponds to the lower bevel 242 of theprevious embodiment. Thus, portions 240 and 238 of the abutment heads ofthe previous two embodiments are eliminated and instead are provided onthe head of the main body (upper part of cuff region 315 and outer bevel316). Other portions of the abutment head 314 are identical to theprevious embodiments, and like reference numbers are used for like partsas appropriate.

In this embodiment, the abutment head 314 is removably secured to themain body in the same manner as described above in connection with theprevious embodiment. Shaft 306 is inserted in bore 300 and the lowerthreaded end portion of the shaft is threaded into the threaded lowerportion 304 of bore 300 so that the lower part of enlarged end portion318 seats in cup shaped seat 298 with the lower bevel 320 engaging thebeveled inner rim 299 of seat 298. In this embodiment, the line ofseparation or connection between the two parts is located at point 322,i.e. above the tissue level 324 defined by the upper end of tissue cuff315. As in the previous embodiments, the lower end of cuff 315 definesthe approximate bone level 325 below which the shaft 295 of the mainbody engages in endosseous bone.

In the two previous embodiments, the line of connection between the mainbody and the abutment member or head is located in the cuff region (seereference number 260 in FIGS. 31 and 32 and in FIG. 35), and thus belowthe tissue level (see FIG. 32). The advantage of the design in FIGS. 39and 40 is that the line of connection between the two parts of theimplant is not located in the cuff region of the implant, but instead istotally separate and above the surrounding tissue or gum, eliminatingany junction along the outer diameter of the tissue cuff, so that theabutment member or head can be replaced by the dentist without anydisturbance of the tissue.

FIGS. 41 to 44 illustrate another embodiment of a two piece implant 330in which the threaded connection between the parts is replaced with ataper press or taper lock fit between the parts. Some portions of thetwo piece implant 330 of this embodiment are identical to equivalentportions of the previous embodiments, and like reference numbers havebeen used for like portions as appropriate. Two piece implant 330comprises a main body 332 which has a modified upper end portion 334 anda shaft 335, and an abutment head 336. The shaft 335 is designed forosseointegration in a prepared bore in a patient's jaw bone and hassimilar threaded regions to the shafts 114 and 295 of the previousembodiments, and like reference numbers have been used as appropriate.The upper end portion 334 has a hex bore 225 as in the first embodiment,while the threaded boss 224 of the first embodiment is replaced by agenerally cylindrical upper portion 338 terminating in an upper taper orbevel 339. A cement groove 340 is located in the cylindrical upperportion, and an upwardly facing, outer taper fit portion 342 is locatedat the lower end of the cylindrical portion 338.

The abutment head 336 has a through bore as in the first embodiment, butthe internal threads 230 are replaced by a cylindrical portion 344followed by a lower taper fit portion 345 at the lower end of thethrough bore. Taper fit portion 345 faces the taper fit portion 342 onthe first end portion of the main body 332. The taper of the twoportions 342 and 345 match one another and are pressed onto therespective parts of the implant 330 during manufacture. In order tosecure the two parts of the implant together, the abutment member boreis engaged over the cylindrical upper portion 338 of the main body andthe parts are pressed together to produce a taper fit or taper lockbetween portions 342 and 345.

The upper end of the through bore in abutment head 336 comprises asocket 232 with an inner rounded rim 233 as in the previous embodimentswhich is designed for releasable snap engagement with the post or shaft234 of a male or retention member 250 as illustrated in FIGS. 31 and 32.The outer surface of the abutment head has a rounded upper end 236followed by an indented or waist portion 237 identical to that of theprevious three embodiments, which together form an outer locatingportion designed for releasable snap engagement with the skirt 258 of amale or retention member 250 as described above in connection with theembodiment of FIGS. 27 to 32. The waist portion 237 is followed by anouter tapered shoulder 346 and a cuff portion 348. Thus, in thisembodiment, the entire cuff portion is located on the abutment head,unlike the previous three embodiments where only part of the cuff waslocated on the abutment head (embodiments of FIGS. 27 to 32 and 33 to38), or the entire cuff was located on the head or end portion of themain body (embodiment of FIGS. 39 and 40).

Once the abutment head has been attached to the main body and the mainbody is sufficiently secured in the bone, a suitable male or retentionmember in a denture or dental appliance can be releasably attached tothe abutment head, as described above in connection with the embodimentof FIGS. 27 to 32, and the appliance can be repeatedly snapped into andout of engagement with the abutment head as desired by the patient. Ifthe attachment or locating surfaces of the abutment head become too wornfor reliable attachment to mating male member in the dental appliance,the abutment head can be removed by the dentist using a tool thatengages in the socket 232 and uses upward pressure rather than rotationto release the taper lock and disconnect the removable abutment headfrom the main body of the implant. This can be done without disturbingthe implant, and a new abutment member can then be engaged over the headportion of the main body. Cement can be placed into the cement groove340 before engaging the abutment head over the cylindrical portion 338to allow the replacement abutment head to be cemented in place by thedentist.

FIGS. 45 to 49 illustrate another embodiment of a two piece mini implant400. Mini implant 400 comprises a main body 402 with a first end portion404 and an integral threaded post or shaft 405 extending from the firstend portion, and a separate abutment head 406 which is removablysecurable to the main body. The implant is of identical or similarmaterials to the previous embodiments. In this embodiment, the abutmenthead 406 has an enlarged end portion 420 and a threaded post 418. Thefirst end portion 404 of the main body has an external tool engagingformation 408 of hexagonal shape, rather than an internal hex portion225 as in the previous embodiments, with taper or bevel 410 at the firstend of the hex formation 408. An annular cuff 412 followed by aninwardly tapering portion 414 extends from the hex formation 408 tothreaded post 405. Post 405 has three equally spaced arcuate indents orflutes 415, for self-tapping when the main body is threaded into aprepared bore in a patient's jaw bone. The first end portion 404 has aninwardly projecting, threaded bore 416 for threaded engagement with thethreaded post 418 of abutment head 406.

Abutment head 406 is similar in some respects to the abutment head 318of FIGS. 39 and 40, and like reference numbers are used for like partsas appropriate. However, the threaded post 418 is shorter, and theenlarged end portion 420 has an end face with a generally conical,inward taper 422 for engagement with the bevel or taper 410 at the firstend of main body 402, as seen in FIG. 49. As in some of the previousembodiments, end portion 420 has a socket 232 with an inner rounded rim233 which is designed for releasable snap engagement with the post orshaft 234 of a male or retention member 250 as illustrated in FIGS. 48and 49. The outer surface of the abutment head has a rounded upper end236 followed by an indented or waist portion 237 identical to that ofFIGS. 27 to 32 and 35 to 40, which together form an outer locatingportion designed for releasable snap engagement with the skirt 258 of amale or retention member 250, as seen in FIG. 49.

The main body 402 of the implant 400 is first installed in a preparedbore in a patient's jawbone, with the hex formation 408 gripped by asuitable hex driver tool or wrench which can be used to thread the post405 into a prepared bore in the jaw bone, cutting threads into the boneas it is installed. The threaded post may be coated by any suitablecoating material prior to installation, as is known in the field ofendosseous implants. The abutment head may be secured to the main bodybefore performing this procedure, using a suitable tool or driverengaging in the socket 232 as described above in connection with thepreceding embodiments. The post 418 is threaded into bore 416 until thetapered lower face 422 of the upper end portion is seated against bevel410, reduce lateral stress on the thread connecting the two parts.

After osseointegration is complete, the abutment head is engaged with acap male or retention member 250 which is in swivel engagement in a cap252, as illustrated in FIGS. 48 and 49. Cap 252 is secured in a recessin a denture or dental appliance in the same way as illustrated in FIG.32 for the embodiment of FIGS. 27 to 32. In FIGS. 48 and 49, theretention member 250 is in hinging, snap engagement in cap 252 andreleasably snap engaged over the outer locating surface portion 236 ofabutment head 406. At the same time, post or shaft 234 is in snapengagement in socket 232.

In another embodiment of a two-piece implant, the outer locating surfaceon the abutment head may have a first set of at least two axially spacedsnap engaging formations while the inner locating surface of theretention member has a second set of at least two axially spaced snapengaging portions for releasable snap engagement with the snap engagingformations on the locator, as illustrated for a one-piece implant in theembodiment of FIGS. 22 to 26. One of the sets of snap engagingformations may comprises spaced annular projections or ribs on one ofthe locating surfaces while the other set comprises spaced annulargrooves for snap engagement over the annular projections or ribs. Thepost may be omitted in this embodiment, or the post may be included foradditional assistance in aligning the dental appliance when placed inthe mouth.

In each of the embodiments of FIG. 27 to 49, a two piece mini implanthas a separate, removably attached abutment head designed for snapengagement with a retention member retained in a cap in a dentalprosthesis. The main body can be directly implanted into a prepared borein the jawbone. This expedites delivery of a finished denture, partialdenture, or other dental prosthesis to a patient. At the same time,because the mini implant is made in two parts, the abutment head can bereplaced as needed when the attachment or locating surfaces become tooworn to work properly. This is an improvement over a one piece miniimplant which would have to be completely removed and replaced with anew implant or altered to continue proper usage, requiring considerabletime and expense.

Two or more one or two piece mini implants may be placed at selectedlocations in a patient's mouth, depending on the size and location ofthe dental prosthesis to be installed. Bores are first prepared atsuitable locations in the jaw bone, and the threaded shafts of the mainbodies of the implants are threaded into the bores. The shafts or postsmay first be treated with suitable coating and/or adhesive materials.Once installed, the locating portions of the abutment heads projectabove the bone and the gum level for snap engagement in opposingretention members which are in swivel engagement with caps secured inthe dental appliance. The resilient nylon or plastic retention membersremain in static engagement with the abutment heads of the implants whenthe appliance is in place, while the metal caps have a full range ofrotational or swivel movement over the retention members while thedental appliance is in use, and can compensate for any misalignmentbetween implants. At the same time, the wearer can readily remove theappliance by snapping the retention members off the locating portions ofthe abutment heads as necessary for cleaning purposes, and can easilyreplace the appliance by urging the retention members onto the abutmentheads of the aligned implants until they snap into place.

The abutment heads of the above embodiments are designed for both innerand outer snap engagement with a mating male or retention member in adental appliance which has an outer skirt for snap engagement over anouter locating surface on the abutment head and an inner post for snapengagement in the upper end socket in the abutment head. However,different abutment heads may be provided which have different attachmentor locating surfaces designed for engagement with other types of male orretention members. In one embodiment, the inner locating surface of theskirt and the outer locating surface portion of the abutment head haveinterengageable snap formations and the retention member is releasablysnap engaged over the abutment head. Both an inner snap engagementbetween the post and socket and an outer snap engagement between thecavity and outer locating portion of the abutment head may be providedin other embodiments, as described above in connection with thedrawings, while in others only an inner snap engagement is provided.

The main body of the implant in the above embodiments has a shaftdesigned for threaded engagement in a bore in the jaw bone andsubsequent osseointegration in the jaw. In alternative embodiments,different types of thread may be used, the thread cutting flats may beremoved, or the threads may be replaced with other types of engagementformations for attachment in the bone.

The above description of the disclosed embodiments is provided to enableany person skilled in the art to make or use the invention. Variousmodifications to these embodiments will be readily apparent to thoseskilled in the art, and the generic principles described herein can beapplied to other embodiments without departing from the spirit or scopeof the invention. Thus, it is to be understood that the description anddrawings presented herein represent a presently preferred embodiment ofthe invention and are therefore representative of the subject matterwhich is broadly contemplated by the present invention. It is furtherunderstood that the scope of the present invention fully encompassesother embodiments that may become obvious to those skilled in the artand that the scope of the present invention is accordingly limited bynothing other than the appended claims.

The invention claimed is:
 1. A dental assembly comprising: a) anendosseous dental implant comprising: (i) a first end portion having atop and a bottom, the first end portion comprises: (1) an externalprojection extending from the top of the first end portion forreleasable engagement with an abutment member, wherein the abutmentmember has an external lower bevel portion; and (2) an annular cuffportion defining an annular seat having a recessed, inwardly taperedbevel surface, wherein the tapered bevel surface surrounds the externalprojection; and wherein the lower bevel of the abutment contacts andseats on tapered bevel surface of the annular seat to form a line ofconnection when the abutment member is releasably engaged with theexternal projection, wherein the line of connection is located slightlybelow a patient's gum line when the implant is secured in the mouth ofthe patient; and (ii) a threaded post which extends from the bottom ofthe first end portion for direct engagement into the patient's bone ortissue; and b) an abutment with an internally threaded bore forthreadable engagement with the external projection.
 2. A dental assemblycomprising: a) an endosseous dental implant comprising: (i) a first endportion having a top and a bottom, the first end portion comprises: (1)an external projection extending from the top of the first end portionfor releasable engagement with an abutment member, wherein the abutmentmember has an external lower bevel portion; and (2) an annular cuffportion defining an annular seat having a recessed, inwardly taperedbevel surface, wherein the tapered bevel surface surrounds the externalprojection; and wherein the lower bevel of the abutment contacts andseats on tapered bevel surface of the annular seat to form a line ofconnection when the abutment member is releasably engaged with theexternal projection, wherein the line of connection is located slightlybelow a patient's gum line when the implant is secured in the mouth ofthe patient; and (ii) a threaded post which extends from the bottom ofthe first end portion for direct engagement into the patient's bone ortissue; b) an abutment; and c) a cap to be secured in a recess in adental appliance, wherein the cap has an inner cavity for releasableengagement with the abutment.
 3. A method of anchoring a dentalappliance in a patient's mouth, comprising: a) securing one or moreendosseous dental implant directly into a patient jaw bone; wherein theimplant comprises: (i) a first end portion having a top and a bottom,the first end portion comprises: (1) an external projection extendingfrom the top of the first end portion for releasable engagement with anabutment member, wherein the abutment member has an external lower bevelportion; and (2) an annular cuff portion defining an annular seat havinga recessed inwardly tapered bevel surface, wherein the tapered bevelsurface surrounds the external projection; and wherein the lower bevelof the abutment contacts and seats on tapered bevel surface of theannular seat to form a line of connection when the abutment member isreleasably engaged with the external projection; and (ii) a threadedpost which extends from the bottom of the first end portion for directengagement into the patient's bone or tissue; b) engaging an abutmentwith the external projection of the implant; wherein the abutment has aninternally threaded bore and the external projection has externalthreads for threaded engagement with the internally threaded bore; andwherein the line of connection is located is slightly below a patient'sgum line when the implant is secured in the mouth of the patient: and c)securing the dental appliance to the abutment.
 4. An endosseous dentalimplant comprising: a) a first end portion having a top and a bottom,the first end portion comprises: (i) a threaded external projectionextending from the top of the first end portion for releasableconnection and threaded engagement with an abutment member, wherein theabutment member has a bore having a lower threaded end portion and anexternal lower bevel portion; and (ii) an annular cuff portion definingan annular seat having a recessed, inwardly tapered bevel surface,wherein the tapered bevel surface surrounds the external projection; andwherein the lower bevel of the abutment contacts and seats on taperedbevel surface of the annular seat to form a line of connection when theabutment member is releasably engaged with the external projection,wherein the line of connection is located slightly below a patient's gumline when the implant is secured in the mouth of the patient; and b) athreaded post which extends from the bottom of the first end portion fordirect engagement into the patient's bone or tissue.
 5. The implant ofany of claims 4, wherein the threaded post comprises a single leadthread or multiple lead threads.
 6. The implant of claim 4, wherein thethreaded post comprises two successive threads of different pitch. 7.The implant of any of claims 4, wherein the threaded post comprisesopposing axial cuts adapted for self-tapping into the patient's bone ortissue.
 8. The implant of any of claims 4, wherein the dental implanthas a maximum outside diameter between about 1.5 mm and about 4.0 mm. 9.The implant of any of claims 4, wherein the annular cuff portion may beof different heights to accommodate different tissue depths.
 10. Theimplant of any of claims 4 wherein the external projection has atool-receiving bore extending inwardly from the upper end of theprojection.